Methods and systems for ultra-precise measurement and control of object motion in six degrees of freedom by projection and measurement of interference fringes

Abstract

A system and method for active visual measurement and servo control using laterally sampled white light interferometry (L-SWLI) for real-time visual tracking of six-degree-of-freedom (6 DOF) rigid body motion with near-nanometer precision. The visual tracking system is integrated with a 6 DOF motion stage to realize an ultra precision six-axis visual servo control system. Use of L-SWLI obtains the complete pose of the target object from a single image frame to enable real-time tracking. Six-degree-of-freedom motions are obtained by measuring the fringe pattern on multiple surfaces of the object or from a single surface with additional information gained from conventional image processing techniques.

1. A system for determining the direct measurement of an object's pose with six degrees of freedom (DOF), the system comprising:
 at least one computer programmed to calculate six degrees of freedom of an object's motion relative to a fixed reference plane and/or an object's position relative to a fixed reference plane by fringe pattern analysis; 
 a broad band illumination-based interferometer; and 
 at least one image capture device capable of capturing and transferring images to the at least one computer, 
 wherein the broad band illumination-based interferometer is optically coupled to the at least one image capture device, 
 wherein the system determines the motion and/or position of the object relative to a fixed reference plane, and 
 wherein the system determines an object's rose with six degrees of freedom (DOF) from an image captured by the at least one image capture device. 
 
   
   
     2. The system of  claim 1 , wherein the system operates in real time. 
   
   
     3. The system of  claim 1 , wherein the broad band illumination is white light. 
   
   
     4. The system of  claim 1 , wherein the at least one image capture device is at least one CCD camera. 
   
   
     5. The system of  claim 1 , wherein the system is designed to conduct real time measurement object's rigid body motion with six degrees of freedom (DOF). 
   
   
     6. The system of  claim 1 , wherein the system is utilized to provide positioning and alignment data. 
   
   
     7. The system of  claim 1 , wherein the system is utilized as a motion sensor in a visually-guided motion control system. 
   
   
     8. The system of  claim 1 , wherein the fringe pattern analysis is accomplished via programming the computer to apply a two dimensional Fourier Transform to a fringe pattern generated from the object to be measured. 
   
   
     9. A system for determining the direct measurement of an object's pose with six degrees of freedom (DOF), the system comprising:
 at least one computer programmed to calculate six degrees of freedom of an object's motion relative to a fixed reference plane and/or an object's position relative to a fixed reference plane by fringe pattern analysis; 
 a laser illumination-based interferometer; 
 a broad band illumination-based interferometer; and 
 at least one image capture device capable of capturing and transferring images to the at least one computer, 
 wherein the broad band illumination-based interferometer is optically coupled to the at least one image capture device, 
 wherein the system determines the motion and/or position of the object relative to a fixed reference plane, and 
 wherein the system determines an object's pose with six degrees of freedom (DOF) from an image captured by the at least one image capture device. 
 
   
   
     10. The system of  claim 9 , wherein the system operates in real time. 
   
   
     11. The system of  claim 9 , wherein the broad band illumination is white light. 
   
   
     12. The system of  claim 9 , wherein the at least one image capture device is at least one CCD camera. 
   
   
     13. The system of  claim 9 , wherein the system is designed to conduct real time measurement object's rigid body motion with six degrees of freedom (DOF). 
   
   
     14. The system of  claim 9 , wherein the system is utilized to provide positioning and alignment data. 
   
   
     15. The system of  claim 9 , wherein the system is utilized as a motion sensor in a visually-guided motion control system. 
   
   
     16. The system of  claim 9 , wherein the fringe pattern analysis is accomplished via programming the computer to apply a two dimensional Fourier Transform to a fringe pattern generated from the object to be measured. 
   
   
     17. A Fourier Transform-based system for determining the direct measurement of an object's pose with six degrees of freedom (DOF), the system comprising:
 at least one computer programmed to calculate six degrees of freedom of an object's motion relative to a fixed reference plane and/or an object's position relative to a fixed reference plane by fringe pattern analysis; 
 a broad band illumination-based interferometer; and 
 at least one image capture device capable of capturing and transferring images to the at least one computer, 
 wherein the broad band illumination-based interferometer is optically coupled to the at least one image capture device and wherein the system determines the motion and/or position of the object relative to a fixed reference plane using a two-dimensional Fourier Transform analysis. 
 
   
   
     18. The system of  claim 17 , wherein the system operates in real time. 
   
   
     19. The system of  claim 17 , wherein the broad band illumination is white light. 
   
   
     20. The system of  claim 17 , wherein the at least one image capture device is at least one CCD camera. 
   
   
     21. The system of  claim 17 , wherein the system is designed to conduct real time measurement object's rigid body motion with six degrees of freedom (DOF). 
   
   
     22. The system of  claim 17 , wherein the system is utilized to provide positioning and alignment data. 
   
   
     23. The system of  claim 17 , wherein the system is utilized as a motion sensor in a visually-guided motion control system.